That is very wired. Do you have Steam VR installed and up to date?
What do you mean exactly with “end VR”? Just pressing ctrl+tab in the sim or are you doing additional things?
What do you mean exactly with “restart VR”? Just pressing ctrl+tab again in the sim to go back to VR or are you doing additional things?
Do you use “Virtual Desktop” for streaming to the headset?
Usually the Pico 4 is quite trouble-free for use with a PC and steam VR in particular.